Chain saw



FIG. 1 is a left perspective view of the chain saw;

FIG. 2 is a rear view of the chain saw shown in FIG. 1;

FIG. 3 is a front view of the chain saw shown in FIG. 1;

FIG. 4 is a left side view of the chain saw shown in FIG. 1;

FIG. 5 is a right side view of the chain saw shown in FIG. 1;

FIG. 6 is a top view of the chain saw shown in FIG. 1; and,

FIG. 7 is a bottom view of the chain saw shown in FIG. 1.

The broken lines shown in the drawings represent unclaimed portions of the chain saw and form no part of the claimed design. 

I claim the ornamental design for a chain saw, as shown and described. 